Food Spoilage Fungi Research Articles

Inhibition of Food Spoilage Fungi, Botrytis cinerea and Rhizopus sp., by Nanoparticles Loaded with Baccharis dracunculifolia Essential Oil and Nerolidol.

This study investigates the antifungal potential of encapsulated essential oil (EO) from Baccharis dracunculifolia and nerolidol (NE) within Pluronic® F-127 nanoparticles (NPs). The EO, containing nerolidol, β-caryophyllene, and α-pinene as major bioactive compounds, exhibited superior antifungal activity compared to NE. The NP-EO formulations demonstrated high efficacy against Botrytis cinerea, with inhibition rates ranging from 29.73% to 87.60% and moderate efficacy against Rhizopus sp., with inhibition rates from 11.81% to 32.73%. In comparison, NP-NE showed lower antifungal activity. Both formulations effectively inhibited spore germination, with NP-EO showing greater inhibition compared to NP-NE. The encapsulation efficiency was significantly higher for NP-EO (80.1%) as compared to NP-NE (51.1%), attributed to the complex composition of EO facilitating better encapsulation and retention. Stability studies indicated that both NP formulations were stable at 25 °C for at least 15 days and exhibited changes in particle size and the formation of smaller particle populations at other temperatures (4 °C and 37 °C). Hemolytic activity was low across all NPs, suggesting their safety for food applications. The findings underscore the efficacy and applicability of EO-encapsulated NPs in extending food shelf life and maintaining product quality. The controlled and prolonged release of active compounds, coupled with their antifungal activity and safety, suggests that these NPs represent a promising and innovative approach for food preservation and active packaging development.

Biopreservative Potential of Lemon Grass (Cymbopogon citratus) Oil against Common Food Spoilage Fungi

Biopreservative Potential of Lemon Grass (Cymbopogon citratus) Oil against Common Food Spoilage Fungi

Identification of Food Spoilage Fungi Using MALDI-TOF MS: Spectral Database Development and Application to Species Complex.

Fungi, including filamentous fungi and yeasts, are major contributors to global food losses and waste due to their ability to colonize a very large diversity of food raw materials and processed foods throughout the food chain. In addition, numerous fungal species are mycotoxin producers and can also be responsible for opportunistic infections. In recent years, MALDI-TOF MS has emerged as a valuable, rapid and reliable asset for fungal identification in order to ensure food safety and quality. In this context, this study aimed at expanding the VITEK® MS database with food-relevant fungal species and evaluate its performance, with a specific emphasis on species differentiation within species complexes. To this end, a total of 380 yeast and mold strains belonging to 51 genera and 133 species were added into the spectral database including species from five species complexes corresponding to Colletotrichum acutatum, Colletotrichum gloeosporioides, Fusarium dimerum, Mucor circinelloides complexes and Aspergillus series nigri. Database performances were evaluated by cross-validation and external validation using 78 fungal isolates with 96.55% and 90.48% correct identification, respectively. This study also showed the capacity of MALDI-TOF MS to differentiate closely related species within species complexes and further demonstrated the potential of this technique for the routine identification of fungi in an industrial context.

In vitro characterization of lactic acid bacteria from Indian fermented rice for probiotic applications

AimTo investigate probiotic attributes of lactic acid bacteria (LAB) isolated from under-explored Indian fermented rice for potential application in consumer health and functional product development. Methods and resultsThe isolates endured conditions resembling gastric stress, including pH (3), bile salt (4%), NaCl (6%), and phenol (0.6%). The selected isolates were identified as L. fermentum and L. plantarum strains by 16 S rRNA sequencing. In a simulated gastrointestinal tract (GIT), isolate SR1 outperformed other cultures in terms of viability. Auto-aggregation, and mucin adhesion abilities were tested for colonization potential. In which, compared to other isolates, MCR1 showed greater mucin adherence. SR1 and MCR1 showed higher percentages of auto-aggregation than GG. The auto-aggregation ranged from 9% to 88%., the levels significantly increase after 24 h incubation. The lower Salt aggregation Test (SAT) values indicated efficient hydrophobicity necessary for persistence in GIT and competitive inhibition to pathogens. All the isolates displayed considerably higher galactosidase activity than GG, isolate FCR2 expressed the highest, up to 613±0.92 Miller’s unit/ml activity. The probiotic candidates displayed broad spectrum antimicrobial activity against food-spoilage fungi and entero-pathogens. The study of safety aspects such as hemolytic, DNase activity, antibiotic susceptibility confirmed unavailability of any virulent factor. ConclusionThe isolates developed substantial galactosidase activity and significant broad-spectrum antibacterial activity. These characteristics make isolates an effective commercial option for β-galactosidase production in the food sector to create low-lactose or lactose-free products. Overall, the isolates' capacity for survival, colonization, and other useful traits may be of commercial relevance. Additionally, isolates can be researched for the production of antibacterial agents and in vivo studies for development of future functional food products. Moreover, these findings lay a robust groundwork for future exploration in probiotics, functional foods and nutraceuticals, while also shedding light on the mechanisms underlying the health benefits of the specified traditional food source. SignificanceThis investigation uncovered potential probiotic LAB of Indian fermented rice origin. By doing so, it expands our understanding of LAB diversity and presents promising candidates for applications in gut health improvement, functional food development, and exploration of natural antibacterial solutions.

Investigating the effect of acoustic waves on spoilage fungal growth and shelf life of strawberry fruit

The effects of acoustic waves on growth inhibition of food spoilage fungi (Aspergillus niger, Aspergillus flavus, Aspergillus parasiticus and Botrytis cinerea) on the medium and strawberry surfaces were investigated. Firstly, single-frequency sound waves (250, 500, 1000, 2000, 4000, 8000, 12,000 and 16,000 Hz) were induced on inoculated medium with fungi spores for 24 h and growth diameter of each mold was evaluated during the incubation period. In the second stage, the sound waves with two frequencies of 250 Hz and 16,000 Hz were induced on inoculated strawberries with fungi spores at 5 °C for different times (2, 4, 6, 8 and 10 days). The results from the first stage indicated that the sound waves inhibited the growth of A. niger (20.02%) at 250 Hz and B. cinerea (4/64%) at 4000 Hz on potato dextrose agar (PDA) surface. Also, comparison of the growth diameter of some species of Aspergillus revealed various responses in presence of 250 Hz frequency. In the second stage, applying a frequency of 250 Hz over a period of 10 days proved to be more effective in inhibiting the growth of A. niger and B. cinerea on strawberries inoculated with fungal spores. Consequently, the shelf lives of the strawberries significantly increased to 26 days and 18 days, respectively, under this treatment. Based on the findings, it is concluded that sounding with acoustic waves can be used as a green and cheap technology along with other technologies to improve food safety.

Chemical composition and antifungal activity of Capsicum pepper aqueous extracts against plant pathogens and food spoilage fungi.

Capsicum pepper is a rich source of phytochemical compounds such as capsaicinoids, phenols, flavonoids, and so forth. Due to their antimicrobial and antioxidant potential all of these compounds have been assessed and used for both human and plant health benefits. Herein, three fresh varieties of Capsicum annuum (Cacho de Cabra, Bell pepper, and Hungarian Wax varieties) and one fresh and ripe variety of C. baccatum (Cristal) were evaluated. Capsaicin, dihydrocapsaicin, nordihydrocapsaicin and the phenolic content of Capsicum spp. extracts were characterised. The antifungal potential of capsaicinoids and antioxidant activities, and the ecotoxicity of each Capsicum spp. extract, using the model Galleria mellonella, were also evaluated. Phytochemical analyses showed that the Cristal and Hungarian Wax varieties presented the highest amount of capsaicin, dihydrocapsaicin, and nordihydrocapsaicin; while Bell Pepper had the highest phenol content and antioxidant activity. Capsaicinoids' standards and Capsicum spp. extracts showed fungistatic activity against the fungal strains assessed. For the fungal strains assessed, the fungistatic activities of capsaicinoids' standards were higher than those observed in Capsicum spp. extracts. The Hungarian Wax extracts inhibited slightly the growth of Aspergillus niger MUM05.11 and Fusarium oxysporum MUM16.143. Similarly, A. niger, F. oxysporum, Rhizopus arrhizus MUM16.05 and Alternaria sp. UFRO17.178 had their growth retarded by the use of Cacho de Cabra and Cristal extracts. Noticeable changes were observed in the fungal strains' morphologies, such as the presence of fragile fungal structures, pigmentation loss, variation in the reproductive structures size and the conidia number. Capsicum extracts weaken the growth of fungi, indicating their fungistatic potential. Considering the fungistatic potential and non-ecotoxicity of these extracts, it is possible to suggest their use as a tool for pest management in the agri-food sector, controlling the growth and reproduction of fungi without posing a risk to non-target biodiversity.

The impact of inter- and intra-species spore density on germination of the food spoilage fungus Aspergillus niger

Aspergilli can be used to produce food but can spoil it as well. Both food production and spoilage are initiated by germination of the conidia of these fungi that have been introduced by inoculation and contamination, respectively. Germination of these spores includes activation, swelling, establishment of cell polarity, and formation of a germ tube. So far, only quantitative single-species germination studies of fungal spores have been performed. Here, spore germination of the food spoilage fungus Aspergillus niger was studied quantitatively in mono-culture or when mixed with other food-relevant aspergilli (Aspergillus nidulans, Aspergillus terreus, Aspergillus clavatus, and Aspergillus oryzae). In the presence of the germination inducing amino acids proline or alanine, but not in the case of the lowly inducing amino acid arginine, the incidence of swelling and germ tube formation was reduced when 35,000 extra conidia of Aspergillus niger were added to wells containing 5000 of these spores. Adding 35,000 spores of one of the other aspergilli also did not have an effect on germination in the presence of arginine, but the germination inhibition was stronger when compared to the extra A. niger spores in the case of alanine. A similar effect was obtained with proline. Together, results show that the germination of A. niger conidia is impacted by the density of its own spores and that of other aspergilli under favorable nutritional conditions. These results increase our understanding of food spoilage by fungi and can be used to optimize food production with fungi.

Role of mitochondrial farnesyltransferase gene in the prevention of the food spoilage fungi Aspergillus flavus by the antimicrobial natural preservative perillaldehyde

Aspergillus flavus, one of the most widely distributed and abundant genus of Aspergillus worldwide, poses an evident threat as a source of food contamination in grains and cereals. Perillaldehyde (PAE), a volatile essential oil extracted from the stem and leaves of Perilla frutescens L., exhibits potent antifungal activity. In our study, we investigated the role of Cox10, a key enzyme in the heme A synthesis pathway crucial for maintaining mitochondrial function. We found that cox10 is a sensitive gene of A. flavus in response to PAE by gene expression assay and GFP fluorescent localization tagging, and then we found that the deletion of this gene affects the growth and development of A. flavus, but the drug resistance is elevated. Through transcriptome sequencing and its experimental validation, the molecular mechanisms of stress triggered by the deletion of cox10 were further clarified, such as the decrease in intracellular drug content due to the increase in the expression of drug efflux proteins, and the increase in the thickness of cell wall due to the increase in the content of cell wall chitin. Clearly, cox10 plays a critical role in regulating various cellular processes of A. flavus, including growth, reproduction, development, as well as pathogenicity and drug resistance. These significant findings establish a solid theoretical foundation for the development of environmentally friendly, safe, and effective antifungal agents to combat A. flavus contamination.

Antibiofilm activity of LAE (ethyl lauroyl arginate) against food-borne fungi and its application in polystyrene surface coating

Several filamentous fungi species as Fusarium oxysporum or Cladosporium sp. can form biofilms by themselves or by participating in polymicrobial biofilms with bacteria. However, despite the high impact of biofilm on the food industry and the high efforts done to control biofilm produced by bacteria in the food area, there has been little study of strategies to control fungal biofilm in this area. In this study, the antibiofilm activity of the safe antimicrobial compound ethyl lauroyl arginate (LAE) was investigated against food spoilage fungi (Cladosporium cladosporioides, Aspergillus ochraceus, Penicillium italicum, Botrytis cynerea and Fusarium oxyspoum). Finally, the efficacy of a varnish-based coating incorporating LAE and coated onto polystyrene microtiter plates has been evaluated as a strategy to reduce fungal biofilm formation. The results of the 2,3-bis-(2-metoxi-4-nitro-5-sulfofenil)-2H-tetrazoilo-5-carboxanilida (XTT) assay, which measure the biofilm metabolic activity of moulds, demonstrated that LAE reduced significantly the formation of fungal biofilm at concentrations from 6 to 25 mg/L. This reduction was confirmed by the micrographs obtained by scanning electronic microscopy (SEM). In addition, LAE also showed antifungal activity against established biofilms. Particularly, it reduced their metabolic activity and viability at concentrations from 6 to 25 mg/L according to results obtained in the XTT assay and observations made by confocal laser scanning microscopy (CLSM). Finally, active coating incorporating from 2% of LAE proved to reduce significantly the biofilm formation in C. cladosporioides, B. cynerea and F. oxyspoum according to the results obtained in the XTT assay. However, the released studies indicated that the retention of LAE in the coating should be improved to prolong their activity.

The antimicrobial efficacy of native Australian essential oils in liquid and vapour phase against foodborne pathogens and spoilage microorganisms

Foodborne pathogens and spoilage microorganisms are a source of concern for public health and the food industry. Considering the problem of antimicrobial resistance in microbes, controlling these microorganisms using synthetic antimicrobials is challenging, thus, essential oils are a potential natural alternative. Previous studies have predominantly focussed on the antimicrobial activity of essential oils in the liquid phase. However, in this work we report on the in vitro antimicrobial activity of the liquid and vapour phases of essential oils from native Australian plants Tasmanian mountain pepper (Tasmannia lanceolata), lemon myrtle (Backhousia citriodora), as well as the common herb thyme (Thymus vulgaris) against 11 common food spoilage and pathogenic bacteria and fungi. Initial screening was conducted using the disc diffusion assay. The minimum inhibitory concentration (MIC) of the oils was determined using the broth microdilution assay. The vapour phase antimicrobial activity of the oils was assessed using an inverted petri plate assay and the vapour phase MIC (V-MIC) was quantified using a vapour diffusion assay. GC-MS was adopted to elucidate the compositional profile of the oil in liquid phase. Two extraction methods, namely solid-phase microextraction (HS-SPME) and gas tight syringe headspace sampling (HS) coupled with GC-MS were used for profiling the composition of the volatiles. The findings of this study confirmed the antimicrobial activity of the oils in both liquid and vapour phases, with lemon myrtle and thyme generally showing stronger antimicrobial activity than Tasmanian mountain pepper. The activity in liquid phase was generally higher than the volatiles. However, lemon myrtle and Tasmanian mountain pepper berry volatiles were more effective against Aspergillus niger and Saccharomyces cerevisiae, respectively, relative to the liquid phase highlighting their potential as vapour phase antifungals. In the liquid and gas phases, the major compounds in lemon myrtle were Z-citral (neral) and E-citral (geranial). Polygodial and thymol were the major compounds in Tasmanian mountain pepper and thyme in the liquid phase, respectively. However, the main compounds in their volatiles were p-cymene and γ-terpinene. In conclusion, our research indicates the essential oils' potent vapour phase activity, highlighting their potential application in gaseous diffusion-dependent food applications such as active antimicrobial food packaging.

Antifungal efficacy of kenaf seed peptides mixture in cheese, safety assessment and unravelling its action mechanism against food spoilage fungi

This study investigated the preservation efficacy of kenaf seed peptides mixture (KSPM) in extending the shelf-life of cream cheese matrix and the effect on its physicochemical properties. Also, the safety of KSPM towards mammalian cells and the underlying fungicidal mode of action in-vitro and in-silico were assessed. The KSPM at 500 and 1000 mg/kg effectively prolonged the shelf-life of cream cheese for up to 11–21 days when stored at 25 °C and 4 °C, and significantly reduced the inoculated conidia counts by ∼3 log10 conidia/g. The safety assessment showed that KSPM maintained the proliferation of normal cell lines up to 30 mg/mL. The cell surface potential energy and hydrophobicity of fungi were altered due to the potent interactions between the peptides and the cell envelope, with KSPM causing significant fungal cell wall permeability and subsequent disruption of the cytoplasmic membrane integrity. KSPM treatment induced morphological destruction of conidia and mycelium and caused a significant loss of fungal cellular materials including K+, sugar, protein and nucleic acids (DNA and RNA), indicating irreversible damage to the fungal cytoplasmic membrane. The in-silico molecular docking study revealed that the peptides mixture efficiently interacted with fungal mannoprotein via the formation of hydrogen bonding, electrostatic interactions and hydrophobic forces. The molecular dynamics simulation showed that the peptide KPTGMR was tightly embedded into the fungal phospholipid bilayer membrane and inserted into the phosphate head groups which led to the formation of gaps, suggesting a transmembrane pore or channel action mechanism.

Glimpsing the chemical composition and the potential of Myrtaceae plant extracts against the food spoilage fungus Thielaviopsis ethacetica

• Native Brazilian Myrtaceae species are promising against Thielaviopsis ethacetica fungus. • Percentages of mycelial inhibition above 80% were observed. • Two Myrtaceae extracts showed fungistatic action. • Promising Myrtaceae extracts inhibited conidial germination. • 13 metabolites are annotated in the polar extract of Myrcia amazonica. • Flavonoids are predominant in Myrciaria floribunda extract according to LC-HRMS/MS analysis.

Antifungal action of quaternary ammonium compounds against environmental molds isolated from food industries

AbstractMolds are ubiquitously found microorganisms that are usually present as contaminants in food industrial environments. It has been shown that Cladosporium and Aspergillus genera are two of the most abundant and widely distributed in these locations because they are highly resistant species to sanitizing treatments. Hence, the search of antimicrobial compounds that are effective to these types of fungal contamination becomes relevant. The aim of this report was to evaluate the antifungal capacity of two commercial preparations made both with benzalkonium chloride (a first generation QAC) alone and with the addition of glutaraldehyde at different concentrations and contact times. A suspension‐neutralization test was performed employing spores of five strains of both Aspergillus section Nigri and Cladosporium cladosporioides, all isolated from food industries environments. Results have shown that benzalkonium chloride preparation was successful in destroying Cladosporium spores at 5% (v/v) concentration (average 4D value of 9.1 min) but failed in neutralizing Aspergillus propagules at the same conditions. On the other hand, the commercial mixture made of benzalkonium chloride and glutaraldehyde was effective in the inactivation of all food spoilage fungi spores at 1% (v/v) concentration (average 4D value of 1.8 and 8.8 min for Cladosporium and Aspergillus strains, respectively).

Potential of electrolyzed water to inactivate bread and cheese spoilage fungi

Controlling food spoilage fungi remains a challenge for food industries, and regulations on the usage of chemical disinfectants are becoming restrictive. Then, this study aimed to evaluate electrolyzed water (EW) as a sustainable alternative for food spoilage fungi inactivation. The experiment was carried out according to the protocol for testing the antifungal effects of chemical sanitizers by the European Committee for Standardization (CEN), using acidic electrolyzed water (AEW-AAC: 85 ppm; pH: 2.65; ORP: 1120 mV) and a basic electrolyzed water (BEW- pH: 11.12; ORP: −209 mV) to inactivate spoilage fungi strains from bread (Hyphopichia burtonii and Penicillium roqueforti) and cheese (P. roqueforti and Penicillium commune), besides the standard fungi for this type of essay (Candida albicans and Aspergillus brasiliensis). AEW presented a higher antifungal effect, inactivating an average of 89 % of the exposed population when compared to its respective BEW, which inactivates about 81.5 %. In general, the standard strains A. brasiliensis (ATCC 16404) and Candida albicans (ATCC 24433) were more sensitive to both AEW and BEW than the food-spoilage strains. Among those, P. roqueforti strains were the most sensitive, followed by P. commune strains, while H. burtonii strains were the most tolerant. EW can be a sustainable alternative for product surface and facility cleaning with further antifungal action when a sanitization step is not mandatory or needed. Future studies searching for conditions to improve the antifungal action of EW could make their industrial usage more viable.

Drivers of Post-Harvest Aflatoxin Contamination: Evidence Gathered from Knowledge Disparities and Field Surveys of Maize Farmers in the Rift Valley Region of Kenya.

Maize-dependent populations in sub-Saharan Africa are continually exposed to aflatoxin poisoning owing to their regular consumption of this dietetic cereal. Being a staple in Kenyan households, consumption of maize-based meals is done almost daily, thereby exposing consumers to aflatoxicoses. This study assessed awareness levels, knowledge disparities, and perceptions regarding aflatoxin contamination at the post-harvest phase among farmers in the Rift Valley Region of Kenya. Households were randomly selected using a geographical positioning system (GPS) overlay of the agro-ecological zones within Uasin Gishu and Elgeyo Marakwet counties. Face-to-face interviews were conducted in 212 smallholder and large-scale farms. The study documented the demographic profiles of farmers and knowledge, awareness, and perceptions of aflatoxin contamination using a pre-designed structured questionnaire. Most farmers were familiar with aflatoxins and the adverse effects they present to health (61.32%). Almost all the farmers (94.37%) were aware of storage molds and food-spoilage fungi. However, few farmers adopted good post-harvest practices (PHPs), such as avoiding premature harvests (49.8%), using well-ventilated storage spaces (44.6%), grain sorting (30.5%), proper drying of maize (17.8%), and using hermetic bags for storage (30.5%). Conclusively, intensified farmer education is required to train farmers on good PHPs to protect their maize from aflatoxigenic fungi and aflatoxin accumulation.

The Secondary Metabolites and Biosynthetic Diversity From Aspergillus ochraceus.

Aspergillus ochraceus, generally known as a food spoilage fungus, is the representative species in Aspergillus section Circumdati. A. ochraceus strains are widely distributed in nature, and usually isolated from cereal, coffee, fruit, and beverage. Increasing cases suggest A. ochraceus acts as human and animal pathogens due to producing the mycotoxins. However, in terms of benefits to mankind, A. ochraceus is the potential source of industrial enzymes, and has excellent capability to produce diverse structural products, including polyketides, nonribosomal peptides, diketopiperazine alkaloids, benzodiazepine alkaloids, pyrazines, bis-indolyl benzenoids, nitrobenzoyl sesquiterpenoids, and steroids. This review outlines recent discovery, chemical structure, biosynthetic pathway, and bio-activity of the natural compounds from A. ochraceus.

High sorbic acid resistance of Penicillium roqueforti is mediated by the SORBUS gene cluster.

Penicillium roqueforti is a major food-spoilage fungus known for its high resistance to the food preservative sorbic acid. Here, we demonstrate that the minimum inhibitory concentration of undissociated sorbic acid (MICu) ranges between 4.2 and 21.2 mM when 34 P. roqueforti strains were grown on malt extract broth. A genome-wide association study revealed that the six most resistant strains contained the 180 kbp gene cluster SORBUS, which was absent in the other 28 strains. In addition, a SNP analysis revealed five genes outside the SORBUS cluster that may be linked to sorbic acid resistance. A partial SORBUS knock-out (>100 of 180 kbp) in a resistant strain reduced sorbic acid resistance to similar levels as observed in the sensitive strains. Whole genome transcriptome analysis revealed a small set of genes present in both resistant and sensitive P. roqueforti strains that were differentially expressed in the presence of the weak acid. These genes could explain why P. roqueforti is more resistant to sorbic acid when compared to other fungi, even in the absence of the SORBUS cluster. Together, the MICu of 21.2 mM makes P. roqueforti among the most sorbic acid-resistant fungi, if not the most resistant fungus, which is mediated by the SORBUS gene cluster.

Effectiveness of two UV-C light-emitting diodes (LED) systems in inactivating fungal conidia on polyethylene terephthalate

The present study aimed to assess the effects of two UV-C LED systems on three food-spoilage fungi (Hyphopichia burtonii, Penicillium brevicompactum, Aspergillus brasiliensis) that can contaminate food packaging materials. The UV-C LED systems were used at two distinct light intensities (9.0 mW/cm2 and 5.5 mW/cm2) for up to 800 s. Fungal conidia were deposited on polyethylene terephthalate lids as either a single (4–5 log CFU/lid) or a multiple layer of cells (5–6 log CFU/lid) to evaluate any difference due to a potential “shadow effect”. In the tests performed, A. brasiliensis was the most resistant fungus to the effects of UV-C LED irradiation, with its 1D-value varying from 23 to 58 s (9.0 mW/cm2) and from 46 to 58 s (5.5 mW/cm2) regardless of the light source used or the type of inoculum. In contrast, H. burtonii and P. brevicompactum were inactivated within 5 s when a single layer was used, whereas their 1D-values were equal to 2–4 s (H. burtonii) and to 3–13 s (P. brevicompactum) when a multilayer was tested. Given the low fungal contamination of food packaging devices and the possibility of developing tailored LED systems, UV-C LED technology was confirmed as an interesting method of sanitization for food packaging.Industrial relevance: This study provides data on the behaviour of two different UV-C LED systems in inactivating fungal conidia on polyethylene terephthalate surfaces. This study helps to understand how specific factors (e.g., spatial arrangement of cells; fluctuating fungal loads on packaging devices) can influence the UV-C LED system performance and therefore could be useful for both plant manufacturers and food industries to develop tailored UV-C LED systems.

Discovery of Chitin Deacetylase Inhibitors through Structure-Based Virtual Screening and Biological Assays.

Chitin deacetylase (CDA) inhibitors were developed as novel antifungal agents because CDA participates in critical fungal physiological and metabolic processes and increases virulence in soilborne fungal pathogens. However, few CDA inhibitors have been reported. In this study, 150 candidate CDA inhibitors were selected from the commercial Chemdiv compound library through structure-based virtual screening. The top-ranked 25 compounds were further evaluated for biological activity. The compound J075-4187 had an IC50 of 4.24 ± 0.16 μM for AnCDA. Molecular docking calculations predicted that compound J075-4187 binds to the amino acid residues, including active sites (H101, D48). Furthermore, compound J075-4187 inhibited food spoilage fungi and plant pathogenic fungi, with minimum inhibitory concentration (MIC) at 260 μg/ml and minimum fungicidal concentration (MFC) at 520 μg/ml. Therefore, compound J075-4187 is a good candidate for use in developing antifungal agents for fungi control.

AwAreA Regulates Morphological Development, Ochratoxin A Production, and Fungal Pathogenicity of Food Spoilage Fungus Aspergillus westerdijkiae Revealed by an Efficient Gene Targeting System.

Aspergillus westerdijkiae, the producer of ochratoxin A (OTA), which is of worldwide concern, is an import fungal species in agriculture, food, and industry. Here, we got the uridine auxotrophic mutant of A. westerdijkiae by deleting AwpyrG. The ΔAwpyrG could be used for bio-transformation with exogenous AfpyrG expression cassette as a selection marker. In order to enhance the efficiency of gene targeting, Awku70 and Awlig4 were homologously deleted from ΔAwpyrG. The efficiencies of homologous replacement for ΔAwku70 and ΔAwlig4 were 95.7 and 87.0% in the deletion of AwAreA, respectively, demonstrating a drastic increase from 4.3% of the wild type (WT) strain. Furthermore, the function of AwAreA was identified with AwAreA deletion mutant and the control strain ΔAwku70. AwAreA regulated the growth and conidiation of A. westerdijkiae in response to nitrogen sources. The concentration of OTA for ΔAwku70 was in the range of 19.4 to 186.9 ng/cm2 on all kinds of nitrogen sources. The OTA production influenced by the deletion of AwAreA was different based on nitrogen sources. Pathogenicity assays on pears, grapes, salted meat, and cheese showed that AwAreA acted as a negative regulator in the infection of food substrates. Therefore, the genetic methods and engineered strains enable us to substantially expand the use of A. westerdijkiae, one of more than twenty OTA-producing fungi, in the study of mycotoxin biosynthesis and regulation, and consequently to aim at providing new ways for controlling this pathogen.